Polyester resins, particularly polybutylene terephthalate (PBT) and polyethylene terephthalate (PET), are suitable for the preparation of molded articles because of its partially crystalline structure. Molded articles prepared from PBT, as a base resin, and various additives are known to exhibit good mechanical properties when subjected to severe mechanical stress and extreme heat. PBT/PET blends have been combined with other materials to improve the mechanical and chemical properties, i.e. molding characteristics, impact strength, thermal stability, flame stability, warping and surface appearance, for a host of applications. Generally, a plethora of materials have been blended with PBT and PET in an attempt to improve the properties of the blend without detracting from the characteristic properties provided by the resin.
The use of glass fibers as a PET reinforcing material is generally discussed in U.S. Pat. No. 3,368,995 to Furakawa et al. The inclusion of barium sulfate to provide highly filled PET/PBT blends is mentioned in U.S. Pat. No. 5,149,734 to Fisher et al., and U.S. Pat. Nos. 5,214,088 and 5,395,875 to Allen et al. Japan Laid-Open Pat. No. 1-247454, published Oct. 3, 1989 references an impact modifier additive for polyester resin compositions, characterized as a mixture of a copolymer of ethylene/ glycidyl(meth)acrylate and a copolymer of ethylene/(meth)acrylic acid. Lu et al., U.S. Pat. No. 4,341,758 teaches the addition of a nucleating agent to polyester blends to provide smooth, glossy surfaces to molded articles prepared therefrom. Kirsch et al., U.S. Pat. No. 5,298,546 suggests a polyalkylene terephthalate blend containing barium sulfate, reinforcing materials, and an elastomer-modifier based on (meth)acrylates.
It is desirous to provide a PET resin composition that is suitable for the preparation of shaped articles exhibiting a combination of high surface gloss, improved impact strength, high density, and ceramic-like feel. The composition should provide the benefits of a PET-filler material and be a suitable substitute for ceramic materials.